<template>
  <section class="timeline">
    <ul>
      <li
        v-for="(item, i) in activities"
        :key="item.timestamp"
        :class="{ 'in-view': showArr[i] }"
        :style="{
          '--backgroundColor': item.backgroundColor || defaultBackColor,
          backgroundColor: lineBackColor,
        }"
      >
        <div
          :style="{
            backgroundColor: item.backgroundColor || defaultBackColor,
            color: item.color || defaultColor,
          }"
        >
          <time>{{ item.timestamp }}</time
          >{{ item.content }}
        </div>
      </li>
    </ul>
  </section>
</template>

<script>
export default {
  name: "skyTimeline",
  props: {
    activities: {
      type: Array,
      default: () => [],
    },
    lineBackColor: {
      type: String,
      default: "#d4d4d4",
    },
  },
  data() {
    return {
      showArr: [false],
      defaultBackColor: "rgb(255, 208, 75)",
      defaultColor: "#fff",
    };
  },
  created() {
    this.$nextTick(() => {
      this.items = document.querySelectorAll(".timeline li");
      window.addEventListener("load", this.callbackFunc);
      window.addEventListener("resize", this.callbackFunc);
      window.addEventListener("scroll", this.callbackFunc);
    });
  },
  methods: {
    isElementInViewport(el) {
      var rect = el.getBoundingClientRect();
      return (
        rect.top >= 0 &&
        rect.left >= 0 &&
        rect.bottom <=
          (window.innerHeight || document.documentElement.clientHeight) &&
        rect.right <=
          (window.innerWidth || document.documentElement.clientWidth)
      );
    },

    callbackFunc() {
      for (var i = 0; i < this.items.length; i++) {
        if (this.isElementInViewport(this.items[i])) {
          this.$set(this.showArr, i, true);
        }
      }
    },
  },
};
</script>


<style lang="less" scoped>
.timeline ul {
  padding: 50px 0;
}

.timeline ul li {
  list-style-type: none;
  position: relative;
  width: 6px;
  margin: 0 auto;
  padding-top: 50px;
  background: #fff;
}

.timeline ul li::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 0;
  transform: translateX(-50%);
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: inherit;
  z-index: 1;
}

.timeline ul li div {
  position: relative;
  bottom: 0;
  width: 400px;
  padding: 15px;
  border-radius: 4px;
  background: var(--backgroundColor);
}

.timeline ul li div::before {
  content: "";
  position: absolute;
  bottom: 7px;
  width: 0;
  height: 0;
  border-style: solid;
}

.timeline ul li:nth-child(odd) div {
  left: 45px;
}

.timeline ul li:nth-child(odd) div::before {
  left: -15px;
  border-width: 8px 16px 8px 0;
  border-color: transparent var(--backgroundColor) transparent transparent;
}

.timeline ul li:nth-child(even) div {
  left: -475px;
}

.timeline ul li:nth-child(even) div::before {
  right: -15px;
  border-width: 8px 0 8px 16px;
  border-color: transparent transparent transparent var(--backgroundColor);
}

time {
  display: block;
  font-size: 1.2rem;
  font-weight: bold;
  margin-bottom: 8px;
}

/* EFFECTS
–––––––––––––––––––––––––––––––––––––––––––––––––– */

.timeline ul li::after {
  transition: background 0.5s ease-in-out;
}

.timeline ul li.in-view::after {
  background: var(--backgroundColor);
}

.timeline ul li div {
  visibility: hidden;
  opacity: 0;
  transition: all 0.5s ease-in-out;
}

.timeline ul li:nth-child(odd) div {
  transform: translate3d(200px, 0, 0);
}

.timeline ul li:nth-child(even) div {
  transform: translate3d(-200px, 0, 0);
}

.timeline ul li.in-view div {
  transform: none;
  visibility: visible;
  opacity: 1;
}

/* GENERAL MEDIA QUERIES
–––––––––––––––––––––––––––––––––––––––––––––––––– */

@media screen and (max-width: 900px) {
  .timeline ul li div {
    width: 250px;
  }
  .timeline ul li:nth-child(even) div {
    left: -289px;
    /*250+45-6*/
  }
}

@media screen and (max-width: 600px) {
  .timeline ul li {
    margin-left: 20px;
  }
  .timeline ul li div {
    width: calc(100vw - 91px);
  }
  .timeline ul li:nth-child(even) div {
    left: 45px;
  }
  .timeline ul li:nth-child(even) div::before {
    left: -15px;
    border-width: 8px 16px 8px 0;
    border-color: transparent #f45b69 transparent transparent;
  }
}

/* EXTRA/CLIP PATH STYLES
–––––––––––––––––––––––––––––––––––––––––––––––––– */
.timeline-clippy ul li::after {
  width: 40px;
  height: 40px;
  border-radius: 0;
}

.timeline-rhombus ul li::after {
  clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%);
}

.timeline-rhombus ul li div::before {
  bottom: 12px;
}

.timeline-star ul li::after {
  clip-path: polygon(
    50% 0%,
    61% 35%,
    98% 35%,
    68% 57%,
    79% 91%,
    50% 70%,
    21% 91%,
    32% 57%,
    2% 35%,
    39% 35%
  );
}

.timeline-heptagon ul li::after {
  clip-path: polygon(
    50% 0%,
    90% 20%,
    100% 60%,
    75% 100%,
    25% 100%,
    0% 60%,
    10% 20%
  );
}

.timeline-infinite ul li::after {
  animation: scaleAnimation 2s infinite;
}

@keyframes scaleAnimation {
  0% {
    transform: translateX(-50%) scale(1);
  }
  50% {
    transform: translateX(-50%) scale(1.25);
  }
  100% {
    transform: translateX(-50%) scale(1);
  }
}
</style>